My son has a 1992 F150, 4.9L, auto, 4WD, 121K mi. Apparently spun a bearing. It was a royal pain, but we finally got the oil pan off. Here are some pics. Obviously the bearings are toast, and the rod bottom clamp. The question is if we can get by with replacing just those two, or if the rod needs replaced as well. We think the camshaft will be OK. The bearing on the bottom was in worse shape than the top bearing. But both had rotated about 3/4".

Secondary question. If the rod needs replaced, can it be pulled down through the bottom, or should we try from above. I'm not sure it can be pulled down, and sure haven't tried. Hoping to avoid it.

Pics:

 

every rod is line bored to be an exact match to its own cap, so you MUST NOT put a different cap on that rod.
the only way to get it apart is to pull the head off and drive the piston up and out the top.

with how bad the bearing looks, and the journal on the crank having those spin lines like it does, i would advise taking the crank in to a machine shop and having them go over it. at a MINIMUM, that journal will have to be polished up, and that rod replaced.

also, you MUST do your best to figure out why it failed. did it starve for oil, is the main bearing that supplies it with oil, damaged? double check the oil passage between that rod bearing and the nearby main bearing to make sure thats clear. are all the bearings heavily worn and that just happened to be the first one to finally give up?

in my opinion, you would do best to have the crank gone over by a machinist, or replace it - and either way install it with all new bearings.
doing this requires that the engine be separated from the tranny, and is most practical to do if the engine is out of the truck. i'm not sure if it would be possible with the engine in the truck and the tranny separated, but that would be a fight i sure don't want to get into!! pull it out, flip it over, and work on it there

 

If you want any kind of lasting repair you will probably need to remove the engine from the truck. You could smooth up that crankshaft(what you called camshaft) journal and measure it with a micrometer. But I doubt if it would be okay to use. You would still have to remove the head from the engine to get that piston and connecting rod out.

In my opinion the best option would be to pull the engine and take it to a reputable engine shop to be rebuilt. Or if you want to do what repair work you can take the crankshaft and bad rod to the engine shop and go from there.

 

To answer your question, we did not open up any of the other bearings. The engine was knocking low, so we pulled the pan expecting a broken rod. None were, but this one had lateral play--I could wiggle it with my fingers and it made roughly that same sound. The others seemed rock solid.

He had just bought the truck. The auto tranny indicator was broken, and thinks he was doing 70mph with the tranny in 2nd gear.

Not happy news if we have to pull the engine and head. Do-able, but it's at my brother's place--and sounds like it might be there for a while, if we're doing this on weekends... <sigh>

 

You're going to have to pull it to make a repair, any way you slice it. I have found that with this generation of truck (like mine) good used parts are cheap and available. The 4.9 has a very good reliability record, current example notwithstanding! I wouldn't balk at buying a good used engine and setting it in there. Disassembly, replacement gaskets, parts and machine work will be just as expensive and take time. A good used engine can be swapped in as soon as you have the old one out. I would put an oil pan gasket on a replacement engine, any other gaskets can be replaced with the engine in situ.

 

Somewhat catastrophic failure. If there had not been so much damage to the rod/bearing surfaces, it could have been polished and then plastigauged, perhaps with .001 oversize bearing installed. As others mentioned, it's gonna have to be removed from the top and a new rod installed. When damage like this occurs, it can stretch the cap to the rod and no matter what bearing you put in, it won't last.

Swapping in a new motor, if time is limited, may be a better route. You can at least get this one pulled and make decisions on affordable upgrades or replacements, with machine work, and a guaranteed life for it once it's re-assembled. These motors are well known to last over the 300K mark, though unfortuantely this one didn't make it there. It didn't throw the rod and thus the block was saved.

Let us know what happens next.

 

FWIW, my local craigslist market has any engine you can name for $3-500, and even a minimalist repair on yours is likely to be $1000, assuming you do your own labor. not trying to talk you out of it, just shedding light on the wisdom of a used engine.

if you do go this route, i'll expand on cheggie's advice, may as well do the rear main seal and the oil pump too. i once had a used 300 with an oil pump that was going out, sticky pressure relief valve. installed the engine as is (not knowing), and had the fun job of doing it in the truck, where you don't have room to remove the pan.

then once its back on the road, you get to decide if you want to rebuild your old engine, or just drive it as is on the used one you pick up

 

Update. We picked up a 4.9L out of a 91 F250 for $350 today. They had swapped it for a 351 to run 35" tires. Has a fair amount of new parts: both exhaust manifolds, all 6 injectors, plugs, plug wires, distributor, distributor cap and rotor, fan clutch, water pump, rubber-hydraulic engine mounts.

It also includes the ac compressor and complete wiring harness.

We've got a lot of work ahead, but this is the direction we're heading for now...

Thanks for all the feedback.

 

Wow that's a steal, what is the compression like on the new motor?

 

I have no idea on the compression. My brother has many tools in his garage, but a compression tester is not among them. And the engine is not yet to his garage. My other brother found and picked the engine up for us. So we have to go get it Friday.

We're hoping for the best, obviously.

 

Update, we're almost ready to pull the engine, everything is un-attached except the tranny and the fuel lines. The fuel lines feeding into the lines that feed the rail are slightly different between the two engines. Here is the connection point:



I've loosened the retaining clip. I'm just not sure how to disconnect them. Rather than gorilla them off, I thought I'd ask first. Suggestions?

 

Special tool:

As will all this kind of stuff, there are several million versions. You may measure your lines and search through:

Ford tool disconnect

OR the next post might tell you exactly.

But DO NOT apply gorilla grip.....

 

Thanks for the quick reply. Is this the type of tool that Advance Auto might loan?

And if anyone has the size for this 92 4.9L, that would be appreciated!

 

most parts stores or tool stores like harbor freight will have that disconnect tool, or a set of various sizes, for well under $20. its likely that advance or other parts stores will have a loaner, and i'll leave you to judge if the affordable cost is worth the hassle of the loaner, or better to just buy one

 

Even after you get the right tool in there to disengage the spring those connections can come apart hard.
I recently took mine apart and had to grip them with a pair of small channel locks and twist back and forth while pulling. With some patience and care they eventually came apart.
I had to do the same thing with my spare manifold on a bench. Whoever pulled that engine just cut the lines about a foot away from the connection.
It appears the o-rings were just sticky. I wiped them off and put a little light oil on both sides of the connections and they work fine now.